Online ISSN : 2423-8872
Print ISSN : 0029-0181
ISSN-L : 0029-0181
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  • Yutaro Shoji
    Type: Reviews
    2019 Volume 74 Issue 3 Pages 128-136
    Published: March 05, 2019
    Released: August 16, 2019

    The standard model of particle physics predicts that the electroweak vacuum is not absolutely stable if there is no new physics below the Planck scale. It means that our universe is not persistent and it eventually decays into another vacuum. We review how we estimate the lifetime of the electroweak vacuum and show that it is much longer than the age of the universe. We also discuss electroweak baryogenesis and multiverse, which are closely related to the decay of a vacuum.

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  • Kunihiko Kaneko, Chikara Furusawa
    Type: Reviews
    2019 Volume 74 Issue 3 Pages 137-145
    Published: March 05, 2019
    Released: August 16, 2019

    A macroscopic theory for biological adaptation and evolution is presented. By constraint on steady-growth and robustness of a cellular state, adaptive changes in high-dimensional phenotypic state are constrained to a low-dimensional space, which leads to universal laws on concentration changes across all intracellular components and the cellular growth rate. This universal relation is confirmed in numerical simulations of a simple cell model as well as by bacterial experiments. The present theory is extended to evolution, to show that the concentration changes induced by environmental changes are proportionally reduced across different components of a cell by evolution, which is akin to the Le Chatelier thermodynamics principle. Finally, with the aid of a fluctuation–response relationship, this proportionality is shown to also hold between fluctuations caused by genetic changes and those caused by noise. Overall, these results suggest a thermodynamic-like formulation of cellular systems.

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  • Takuya Nomoto, Kazumasa Hattori, Hiroaki Ikeda
    Type: Researches
    2019 Volume 74 Issue 3 Pages 146-151
    Published: March 05, 2019
    Released: August 16, 2019

    Classification of superconducting gap functions in single-orbital systems is indispensable for an analysis of nodal structure in various unconventional superconductors. However, the presence of unusual gap structure that the conventional classification fails to predict due to orbital/site degrees of freedom has been gradually recognized. Here, we show the group-theoretical classification of gap functions in the multi-orbital superconductors with spin-orbit interactions and in non-symmorphic magnetic space groups. The former result clarifies the anomalous momentum dependence of E2u states in D6h , which is possibly realized in spin-triplet UPt3 superconductors. In the latter case, we extend the classification scheme based on space groups to the magnetic crystal and reveal that the line nodes observed in UCoGe and UPd2Al3 are symmetry protected.

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